The EPA has got a new greenhouse calculator.
We did it for our house and came out at about 17 tonnes of green house gasses. We are a bit over 4 tonnes per person. Well under the Australian average.
Our main issues was transport, even though we have small cars, living in the country means we have to drive distances. The other is our split system for heating and cooling. There are a lot more fuel efficient systems out there. Our big bonus was the the solar panels reducing our emissions by about 4 tonnes.